The present disclosure relates to a separator and a battery using the same. In more detail, the present invention relates to a separator insulating a positive electrode and a negative electrode from each other and a battery using the same.
In recent years, because of conspicuous development of portable electronic technologies, mobile phones and laptop personal computers have been recognized as a fundamental technology for supporting the highly computerized society. Research and development regarding high functionalization of these appliances are being energetically advanced, and it has been considered to be problematic that a driving time is shortened because of an increase of power consumption due to the high functionalization.
In order to ensure a driving time on a certain level or more, since it is an essential condition to realize a high energy density of a secondary battery to be used as a driving power source, for example, a lithium ion secondary battery is expected.
In studying realization of high capacity and high safety of the lithium ion secondary battery, when only a related-art polyolefin microporous film is used, it may be impossible to obtain a sufficient performance, and therefore, it is necessary to impart a function to the polyolefin microporous film. As a method of imparting a function to the polyolefin microporous film, there has been proposed, for example, a method of coating resins having different properties from each other on the polyolefin microporous film.
For example, Patent Document 1 (JP-A-2008-243825) discloses a separator composed of a porous film containing a porous substrate for separator prepared by integrally forming tabular particles by a binder resin and a resin having a melting point in the range of from 80 to 130° C. The tabular particles constituting the porous substrate for separator have a heat-resistant temperature of 150° C. or higher, at least a part thereof has heat resistance and electric insulating properties and is electrochemically stable, and a number average particle size of the tabular particles is 0.1 μm or more and not more than 15 μm.
In Patent Document 1, it is described that by using the foregoing separator as a separator for battery such as lithium secondary batteries, the deposition of a lithium dendrite is prevented from occurring due to the presence of an inorganic oxide filler.
Also, Patent Document 2 (JP-A-2008-27634) discloses a separator composed of a porous heat-resistant layer provided on each of the surfaces of a positive electrode plate and a negative electrode plate opposing to each other and a nonaqueous electrolyte, wherein a metal oxide having a particle size distribution at not more than 5.0 μm, a D10 in the particle size distribution measurement of from 0.2 to 0.6 μm and a mode diameter of from 0.80 to 1.25 μm is used as a filler of the porous heat-resistant layer.
In Patent Document 2, it is described that a lithium ion secondary battery having a porous heat-resistant layer is produced stably and in a large quantity.